What's the difference between `linux-oem` and `linux-oem-osp1` kernels, and how are they versioned?

I understand from reading Kernel/OEMKernel that the linux-oem kernel package is supposed to be a more up-to-date kernel package, that includes additional hardware compatibility tweaks for supported devices on top of the standard kernel (linux-generic?). I'm currently running Ubuntu 19.04 and I note that in addition, the package repositories also contain a linux-oem-osp1 metapackage.

Also, the version number of the kernel associated with the linux-oem package appears to suggest it is older than the kernel for linux-generic, which seems contrary to the description in the linked documentation above.

For Ubuntu Desktop 19.04, as of 2019-10-19, the versions appear as follows:

• linux-generic - 5.0.0.32.33
• linux-oem - 4.15.0.1056.60
• linux-oem-osp1 - 5.0.0.1024.27

So, my questions are:

1. What's the difference between linux-oem and linux-oem-osp1?
2. How are both of these packages versioned (in particular, why does linux-oem appear to be based on an older kernel than linux-generic)?

Obviously the "osp1"-package has a later build number, that let's one assume that "sp1" may be a label for "service pack one" or something like that.

However, since the is no official info in the wiki about any regulations how such service releases are made, I would recommend to ask the kernel devs directly via the mailing-list here.

HTH